Bluestein-Based DAFT Implementation on FPGA for AFDM Modulation

초록

To address doubly-dispersive high-mobility channels, affine frequency division multiplexing (AFDM) leverages the discrete affine Fourier transform (DAFT) to achieve full delay-Doppler diversity. While the theoretical advantages of AFDM have been extensively established, practical hardware implementations are still lacking. Therefore, this paper presents a field-programmable gate array (FPGA) implementation of the DAFT utilizing a Bluestein-based convolution approach, which effectively maps arbitrary-length transforms onto standard powerof-two FFT cores by structurally absorbing the inherent AFDM quadratic phase terms into precomputed chirp factors. This allows the modulation parameters to be applied with no extra runtime multiplier cost, preserving the exact affine frequency domain subcarrier spacing while maintaining O(N log N) complexity. The system's real-time feasibility is validated on a PXIe-7902R FPGA module using LabVIEW FPGA, demonstrating its readiness for practical integrated sensing and communications (ISAC) deployments.

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